1. Field of the Invention
This invention relates, generally, to improvements in endotracheal tubes. More particularly, it relates to an endotracheal tube having a temperature sensor that contacts the tongue.
2. Description of the Prior Art
Body temperature is a vital sign that is monitored closely when a patient is under anesthesia. Temperature sensors are sometimes placed on the patient's fingers or toes, but such positions are not suitable for patients having diabetes, low blood pressure, or any other condition that results in poor circulation and hence cool extremities.
The inner ear, however, is an acceptable location for the location of a temperature sensor; thus, many anesthesiologists rely on ear-placed temperature sensors.
To reduce the number of separate instruments that must be used during a medical procedure, many anesthesiologists would prefer to use an endotracheal tube including a built-in temperature sensor if such were available; thus, insertion of the endotracheal tube through the trachea and into the endotracheal tube would also accomplish insertion of a temperature probe and eliminate the need for a temperature probe in the patient's ear or other location on the body.
The conventional wisdom is that a temperature probe inserted into the trachea, past the larynx, will give a very true reading of the patient's temperature because the temperature probe is physically positioned in the interior of the patient's body.
An example of this technology may be seen in U.S. Pat. No. 4,263,921 to Trugillo. In the device shown in that patent, a temperature probe is embedded into the wall of the endotracheal tube near its distal end; this creates a bulge in the wall which contacts the patient's trachea and thus produces a temperature reading from inside the body, i.e., past the larynx.
A good temperature sensor not only provides accurate readings; it also responds quickly to changes in the patient's body temperature. Thus, a temperature probe that provides highly accurate readings which is highly responsive to temperature changes is needed. The prior art, however, when considered as a whole, teaches that the best sensors should be positioned either within the ear or within the patient's body, i.e., near the distal end of an endotracheal tube.